Near Sacramento, California, nearly a dozen people died from opioids in recent weeks.

In March, a batch of illegally made fentanyl, a potent opiate used to treat extreme pain, began making its way through the streets in Sacramento County, Central California. A clear liquid estimated to be 50 times stronger than heroin, the fentanyl was sold to unsuspecting users, according to the state drug enforcement agency. The deadly mixture has lead to 11 deaths in the area and more than 50 overdoses.

“(Fentanyl) is a very strong high and not difficult to manufacture,” says Rachel Anderson, executive director of the Sacramento-area Needle Exchange, which provides clean needles to drug users. “Users are looking for a more potent high and there’s always a distributor ready to provide it.”

The spate of deaths in California is the first time the state has seen so many fatalities in such a short time period linked to fentanyl, but it speaks to a broader opioid addiction — which includes painkillers and heroin. In the American West, addiction to these substances has dramatically increased in the past two decades, and even more rapidly in the last five years.

The spike started a few years after a highly potent prescription painkiller, OxyContin, was introduced in 1995. By the late 2000’s, the Centers for Disease Control and Prevention was reporting widespread over-prescription and high numbers of patients becoming addicted. In 2010, stricter regulations on prescription pain medicine swiftly limited supply. But despite the crackdowns, pain pill abuse is still a major epidemic. What’s more, those regulations have been a primary driver of the increase in heroin addiction.

Across the West, drug overdoses, which include prescription opiates, heroin and other drugs like methamphetamine, have increased. In 2014, an estimated 60 percent of deaths were linked to opiates.

Data: Centers for Disease Control and Prevention. Designed by Paige Blankenbuehler, High Country News.

In 1999, Rio Arriba County in New Mexico was the only Western county that had a drug overdose death rate of more than 20 people per 100,000 residents, the CDC’s highest classification. (While that figure included other drugs like methamphetamine, the CDC estimates that heroin and prescription opiates contribute to approximately 60 percent of drug overdoses.)

Today, New Mexico still has the highest rate of overdose deaths in the West, and ranks fourth in the country. But in the last decade, drug abuse has spread to nearly 200 counties across the West — nearly 50 percent of the region, including more affluent counties like Salt Lake County, Utah, and those with declining economies like Nye County, Nevada. “Traditionally there’s a notion that addiction and substance abuse is more prevalent in metropolitan areas,” says Gary Tsai, medical director of the Office of Substance Abuse Prevention and Control at the Los Angeles County Department of Public Health. “What’s most concerning now is that it touches everyone. (The opioid epidemic) has crept across cultures and ages, into the rural and urban West. It is indiscriminate.”

Opioid overdoses — which include prescription painkillers like OxyContin and hydrocodone, as well as heroin and illegally made fentanyl — have quadrupled since 2000 nationwide. In the West, New Mexico, Alaska, Oregon and Wyoming have experienced the most dramatic increases of heroin and prescription opioid addiction and death. Between 2013 and 2014, Alaska saw a 17 percent increase in overdose deaths. Meanwhile, Oregon and Wyoming deaths have risen 13 percent. Colorado had a 5 percent increase, while Idaho and Utah had smaller increases, according to the CDC and the National Center for Health Statistics.

While national statistics lump opioids and heroin together, the trend of use typically begins with legally obtained painkillers: A person with an injury or other acute pain can visit a dentist, for example, and easily obtain a prescription for an opiate. “The pharmaceutical industry and the approach to treating pain has essentially primed the market for heroin abuse,” says Ted Cicero, a drug researcher and professor of psychiatry at Washington University in Saint Louis.

The widespread availability of such prescriptions led many states to begin implementing prescription drug monitoring programs, statewide electronic databases that allow physicians to see what other prescriptions their patients were taking from other healthcare providers.

In 2010, Colorado became the first state to implement such a program — a system that has cracked down on “doctor-shopping” and long-term prescribing of opiates with a high potential for abuse. By 2011, most states had adopted prescription pill monitoring programs, cutting the supply of legal opiates. But healthcare providers widely agree that many patients who had become addicted to painkillers subsequently turned to heroin to get their fix. According to a 2014 study, 94 percent of people in treatment for opioid addiction say they chose to use heroin because prescription opioids were "far more expensive and harder to obtain."

“We wouldn’t have people turning to heroin if we hadn’t gotten them addicted to prescription opiates,” says Tim Condon, a research professor for the University of New Mexico Center on Alcoholism, Substance Abuse and Addictions.

As the pill crackdown inadvertently created a hole in supply for opiates, another unintended consequence has amplified the growing epidemic in the West: increased supply from Mexico to match demand. Officials in Mexico and the U.S. say Mexico’s heroin production increased an estimated 50 percent in 2014. And Anderson and Condon say that black tar, a potent but cheap form of heroin often produced in Mexico, is the primary type used in many Western states. Eastern and Midwestern states get their heroin from other distribution networks traced to Mexico, and it’s usually powdered, so-called “China white” heroin.

As for the product itself, black tar is more damaging to human health. It’s a sticky, thick substance, which makes it more potent because it’s difficult to cut with other substances, as is more common with powdered drugs. Skin abscesses and infections in its users are more common. “From a public health standpoint, the heroin in the West is much more dangerous,” Anderson says.

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In the West, there’s little indication that the growing rate of heroin and prescription opiate addiction is slowing, Cicero says. To address the problem in California, assemblywoman Susan Talamantes Eggman proposed a bill in early April that would permit local and state health departments to allow legal, supervised use of controlled substances, like heroin, in medical clinics.

Overall, the response to the epidemic in the West has been a sort of “whack-a-mole approach,” says Susan Kingston, coordinator for the Alcohol and Drug Abuse Institute at the Center for Opioid Safety Education in Seattle, Washington. “We’re trying to make any change we can. Big solutions are happening, but they are slow and need a lot of money and political commitment.”

Paige Blankenbuehler is an editorial fellow at High Country News. She tweets@paigeblank